If you provide them a NMC address they will send you your accumulated NMC.
But if you haven't mined at Slush for a very long time this won't be much anyway.
So not sure why you are making such a fuss about it and are calling them bastards.
I have had a NMC address in there since 2018 - I used to mine there a lot. but after a year of seeing that the merged mining was not being paid out (when they stopped right before NMC peaked at $10 to $13 a coin) so the reward can be substantial to some. I asked and was told that it would be a few weeks to get it paid out, after 2 months, I asked again and was given another date. After that, I stopped mining there. Since then they have said numerous times that they were going to pay it out. I am curious what does an exchange have to do with paying out the rewards to the miners? If there is a lack of accepting exchanges, that affects the miners not Slush. So that is another bullshit answer.
the fact that they lie makes them bastards. At least to me.